Abstract: The effect and harm of mercury to the environment and human health, as well as the mechanism of mercury generation and emission in coal-fired power plants, were introduced. The related policy and standards in China and in developed countries were compared, and the main monitoring methods for mercury in flue gas focused. The relatively mature monitoring methods included Ontario Hydro Method (OHM), 30A Method and 30B Method which were developed by US EPA. Combined with the monitoring experiences in China, it was suggested that the standard monitoring methods and equipments should be developed for mercury emission in coal-fired power plants by referring to the experience of developed countries, and the reduction targets and emission standards be formulated based on the emission monitoring data all over the country.